JPH06200383A - Production of stainless steel enamel and high-nickel alloy steel enamel - Google Patents

Abstract

PURPOSE:To develop the stainless steel enamel and high-Ni alloy steel enamel excellent in adhesion at the time of enameling the stainless steel and high-Ni alloy steel by making the glaze to be firstly applied extremely thin. CONSTITUTION:The surface of a member consisting of various stainless steel contg. Cr and Ni and high-Ni alloy steel such as 'Inconel(R)' is enameled. In this case, the glaze to be firstly applied is made extremely thin so that the thickness is controlled to <=20mum after being roasted, the ground coat is discontinuously finished, formed and roasted, and then the ordinary glaze is applied and roasted. An enameled product excellent in surface smoothness and adhesion is obtained without the need for special pretreatment and glaze.

Description

Detailed Description of the Invention

[0001]

The present invention relates to SUS as a base metal.
304, SUS316, SUS310S, SUS320
Not only for stainless steel enamel using stainless steel such as, but also for high nickel alloy steel enamel using high nickel alloy steel as the base metal,
In the following description, the case where stainless steel is used as the base metal will be described. The present invention is a building material, kitchen appliances,
The present invention relates to a stainless steel product such as a bathtub and a pipe for a chemical factory which has been enameled and does not require any special pretreatment, and further relates to a method for producing a stainless steel enamel having excellent adhesion to the surface of the stainless steel.

[0002]

2. Description of the Related Art Stainless steel is used in many fields such as external walls for construction, kitchen products, bathtubs, wash basins, vehicles, etc., because it is rust-resistant and highly corrosion-resistant and does not lose its brightness for a long time. However, in addition to its advantages, stainless steel is prone to rust and crevice corrosion caused by the contact of dissimilar metals, is extremely susceptible to stains, is easily attacked by chlorine ions such as seawater, and cannot be freely colored. It has drawbacks such as Therefore, various methods of eliminating the drawbacks of stainless steel have been studied in the past, and various enameling of stainless steel has been studied. However, the satisfactory results have not been obtained yet. .

Generally, in enamels, it is essential that the base metal is sufficiently oxidized at the firing temperature of the glaze in order for the glaze and the base metal to firmly adhere to each other. Stainless steel is fairly stable at the firing temperature of normal glaze for iron enamels, and the oxidation does not proceed sufficiently to allow glaze to react with the base material, so good adhesion cannot be obtained with stainless steel enamels. Was being considered.

Therefore, as a means for obtaining good adhesion between the stainless steel and the glaze, a method of mechanically or chemically roughening the surface of the stainless steel, and a frit forming the glaze of the stainless steel Studies have been conducted on a method of introducing a special metal oxide that promotes or corrodes oxidation and a method of suppressing the passivation of the chromium oxide layer on the surface of stainless steel by making the firing atmosphere a reducing atmosphere.

As a method of (1), for example, a concave and convex pattern having a roughness of 2 to 30 μm is provided on the surface of the stainless steel by a mechanical or chemical means to further ensure the close contact between the stainless steel and the glaze. Is disclosed (Japanese Patent Publication No. 52-1729), but it is industrially 2 to 30 μm.
It is extremely difficult to identify the means for forming the roughness of the concave surface and its confirmation. In addition, stainless steel is heated in advance in an oxidizing atmosphere to form an oxide film on the surface, and then immersed in an aqueous solution containing divalent nickel ions to evenly attach the nickel ions to the oxide film. A method for improving the adhesion of glaze has been disclosed (Japanese Patent Publication No. 55-30588), but this method has a problem in that two steps are required for pretreatment of stainless steel. It goes without saying that sufficient adhesion cannot be obtained by a simple surface roughening means such as sand blasting, shot blasting, and chemical etching methods that are generally adopted in the enamel industry.

As a method of (1), there is a method of introducing 1 to 3% by weight of molybdenum trioxide into a frit component containing lead, which can be burned at a relatively low temperature (Japanese Patent Publication No. 55-14819).
No.), this method directly burns the transparent glaze on the stainless steel only once to obtain an industrial enamel product that sees through the metallic luster pattern peculiar to stainless steel, and its frit composition has been extremely specified. Is. In addition, glass containing borosilicate as a main component that does not contain a fluorine component should have 5 to 30
An enameled frit having improved adhesion to stainless steel by introducing Fe ₂ O ₃ in weight% is disclosed (Japanese Patent Laid-Open No. 52-810). In order to introduce Fe ₂ O ₃ of
Contamination of the glass melting furnace and kiln is significant, which is very uneconomical for frit production, and a large amount of Fe ₂ contained in the frit.
Since it is an O ₃ component, Fe ₂ O ₃ is precipitated in the glass matrix by repeating firing 2-3 times, and glazes are likely to devitrify, resulting in unstable adhesion.

As the method of (1), the air in the furnace is replaced with nitrogen gas, then the nitrogen gas is replaced with hydrogen gas, and then the stainless steel plate which is rubbed with hydrogen gas is continuously burned or metal powder is used. A method of using glaze added with a milling agent such as an organic compound or a reducing inorganic compound has been disclosed (Japanese Patent Publication No. 64-87).
12), the former is unsuitable for industrial mass production because it uses a special atmosphere furnace, and the latter has a drawback that a gas is generated during baking of enamel and it is difficult to obtain a smooth glaze surface. As described above, stainless steel enamel cannot be said to be a completed technology, and is a technical field in which further improvement is desired.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional method and provides a method for producing a stainless steel enamel having excellent adhesion by a very simple means. Is.

[0009]

According to the present invention, a glaze is thinly rubbed on the surface of stainless steel or a high nickel alloy steel so that the calcined underlay has a thickness of 20 μm or less and is discontinuously finished. A method for producing a stainless steel enamel and a high nickel alloy steel enamel, which is characterized by forming a layer.

[0010]

In the method for producing a stainless steel enamel of the present invention, the glaze prepared by the usual milling compounding is extremely thin on the surface of the stainless steel (the film thickness after firing is 20 μm or less and is discontinuously finished). A stainless steel enamel with excellent adhesion can be obtained by glazing and firing (to form an underlaying layer) and then rubbing and firing with a normal film thickness, so that stainless steel enamel can be obtained. Does not require any special pretreatment other than degreasing. Also, powder electrostatic scrubbing can be used to glaze stainless steel with oil on it, so no pretreatment is required. In the present invention, it is important that the glaze to be glazed first be made extremely thin. The glaze to be glazed first needs to have a film thickness after firing of 20 μm or less, and the glaze must not be continuous and have a glossy finish, and it is necessary to form a discontinuous finish underglaze layer. . Therefore, the surface of the stainless steel obtained by the first firing has a matt dark brown surface state.

In the close contact between the stainless steel and the glaze,
Elements such as iron, chromium, and nickel that compose stainless steel are oxidized during firing, and the viscosity of glaze decreases,
It is considered that the adhesion reaction proceeds by melting these oxides into the glaze. In addition, Japanese Examined Patent Publication 64-87
No. 12 discloses that chromium oxide passivated on the surface of stainless steel suppresses the oxidation of stainless steel, thereby significantly reducing the rate of melting into glaze. As a result of various studies conducted by the inventors of the present invention on the adhesion mechanism of the present invention, the passivation of chromium oxide on the stainless steel surface was suppressed by glazeing the stainless steel surface with an extremely thin glaze and firing the glaze. However, it is considered that good adhesion can be obtained, and that the minute irregularities formed by the discontinuous finish layer can contribute to the adhesion of the enamel.

[0012]

Example 1 A commercially available titanium milk white frit for iron enamel was milled with the milling composition shown in Table 1 to obtain a glaze. The obtained glaze was used to remove oil from a SUS304 test piece (thickness 0.75 mm, 100 × 150 mm)
Approximately 1g on one side (thickness of glaze after firing about 15μm)
It was sprayed in a dry manner, dried and baked at 800 ° C. for 3 minutes. After the test piece was sufficiently cooled, about 5 g of the same glaze was sprayed in a wet state, dried and then baked under the same conditions. The glaze surface after firing was very smooth, and when the adhesion was evaluated by an adhesion tester of ASTM, the adhesion was 90%. In addition, it was confirmed that the peeled portion of the glaze was in a black gray matte state and was in a very strong adherent state. 5 methods for removing oil
Both an air-baking method at 50 ° C. and a wet method using a degreasing agent were tried, but the glaze surface after firing was smooth and the adhesion was good.

[0013]

Example 2 The same experiment as described in Example 1 was carried out by using the dry crushed frit powder so that the powder can be electrostatically rubbed with the titanium opal frit. The frit powder was electrostatically rubbed onto a test piece of SUS304 (the size is the same as that of Example 1) with the oil still attached. The amount of glaze applied at this time was 0.5 g. The glazed state was such that a thin powder was attached to the entire test piece. This test piece was baked at 780 ° C. for 2 minutes and 30 seconds. After the test piece was sufficiently cooled, about 4 g of the same frit powder was applied by powder electrostatic scrubbing, and baked at 780 ° C. for 2 minutes and 30 seconds. The glaze surface of the obtained test piece was smooth, and the adhesion was evaluated by an adhesion tester of ASTM and found to be 95%. In addition, it was confirmed that the peeled part of the glaze had a matte black-gray appearance, and that it was in a strong adherent state.

[0014]

[Embodiment 3] The frit powder prepared in Embodiment 2 is
A thin (about 0.5 g) powder was electrostatically rubbed onto a test piece of SUS304 (the size was the same as that of Example 1) with oil, and the powder was baked at 780 ° C. for 2 minutes and 30 seconds. After the test piece was sufficiently cooled, about 5 g of the glaze used in Example 1 was wet-sprayed and then dried to 800
Baked at 3 ° C for 3 minutes. The glaze surface of the obtained test piece was smooth, and the adhesion was evaluated by an ASTM adhesion tester, and it was 98%. In addition, it was confirmed that the peeled part of the glaze had a matte black-gray appearance, and that it was in a strong adherent state.

[0015]

Example 4 The following experiment was conducted using the glaze prepared in Example 1 while changing the thickness of the glaze to be initially rubbed. A degreased SUS304 test piece (size is the same as in Example 1) was applied with a glazed amount of 1 g, 2
The above glaze was spray-glazed to give g and 3 g. After glazing, it was dried and baked at 800 ° C. for 3 minutes. At this time, a test piece which was not glazed was also baked as a blank. After the test piece has cooled sufficiently,
Approximately 5g of the same glaze is spray-glazed and dried to 800
Baked at 3 ° C for 3 minutes. In addition, the initial glazed amount is 5 g for 1 g so that the whole thickness is the same, 4 g for 2 g, 3 g for 3 g, and 6 g for those not glazed. A test was also conducted in which the amount of glaze applied was changed. The above test results are shown in Tables 2 and 3. From these results, it can be seen that good adhesion can be obtained when the initial glaze amount of 1 g and the thickness of the underlaying layer after firing is 20 μm or less and is discontinuously finished. In addition, it was confirmed in the course of the test that, in the first squeezing, the local thick staking due to the non-uniform squeezing also causes poor adhesion.

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Example 5] Using the glaze prepared in Example 1, test pieces of SUS310S, SUS316, SUS320, and Inconel 600 (size is the same as in Example 1)
Then, after degreasing, about 1 g was sprinkled on one side in a dry manner and baked at 800 to 850 ° C. for 3 minutes. After the test piece was sufficiently cooled, about 5 g of the same glaze was wet-sprayed, dried, and then baked at 800 ° C. for 3 minutes. The glaze surface of the obtained test pieces was smooth, and when the adhesion was evaluated by an adhesion tester of ASTM, all were 90% or more. At the same time, at the same time as the first baking, bake at 800 to 850 ° C without glaze, and after the test piece has cooled sufficiently, similarly spray about 5 g of the same glaze with wet spray and dry. Calcination was performed at 800 ° C. for 3 minutes.
When the obtained test pieces were evaluated for adhesion with an ASTM adhesion tester, all were 0%. The above test results are shown in Tables 4 and 5. From the above results, the applicable range of the base metal of the present invention is not limited to stainless steel, but Inconel 6
It was confirmed that it can also be applied to enamel of high nickel alloy steel such as 00.

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

EFFECT OF THE INVENTION According to the present invention, a special pretreatment is performed according to the method for producing a stainless steel enamel in which the glaze is fired and fired on the stainless steel to which the glaze is thinned and fired first. Thus, it is possible to obtain a product having a smooth surface and excellent adhesiveness without requiring special glaze. This not only greatly simplifies the enamel manufacturing process, but also eliminates the risk of pollution due to the use of special lead-containing frits. Further, since ordinary glaze can be used, it is possible to obtain a stainless steel enamel having a smooth surface with a good surface condition like iron enamel.

Claims (1)

[Claims] 1. In the production of stainless steel enamel and high-nickel alloy steel enamel, a glaze is rubbed on the surface of the steel very thinly so that the calcined thickness is 20 μm or less and the discontinuity is finished. A method for producing a stainless steel enamel and a high nickel alloy steel enamel, which comprises forming a layer.